The treatment of non-insulin dependent type II diabetes remains unsatisfactory despite the introduction onto the market of a large number of oral hypoglycaemic compounds designed to facilitate the secretion of insulin and to promote its action in peripheral target tissues.
During the last ten years, a class of compounds having a thiazolidinedione structure (U.S. Pat. No. 5,089,514, U.S. Pat. No. 5,306,726) has demonstrated a marked anti-diabetic activity by promoting sensitivity to insulin in the target peripheral tissues (skeletal muscle, liver, adipose tissue) of animal models having non-insulin dependent type II diabetes. Those compounds also lower the levels of insulin and levels of lipids in the same animal models and induce in vitro differentiation of preadipocyte cell lines into adipocyte cell lines (A. Hiragun et al., J. Cell. Physiol., 1988, 134, 124–130; R. F. Kleitzen et al., Mol. Pharmacol., 1992, 41, 393–398).
The treatment of preadipocyte cell lines with the thiazolidinedione rosiglitazone brings about induction of the expression of specific genes of the lipid metabolism, such as aP2 and adipsin, and also the expression of the glucose transporters GLUT1 and GLUT4, suggesting that the effect of the thiazolidinediones observed in vivo may be mediated via adipose tissue. That specific effect is obtained by the stimulation of nuclear transcription factors: <<peroxisome proliferator-activated receptor gamma>> (PPAR γ2). Such compounds are capable of restoring sensitivity to insulin in peripheral tissues, such as adipose tissue or skeletal muscle (J. E. Gerich, New Engl. Med., 19, 321, 1231–1245).
Compounds having a thiazolidinedione structure (troglitazone, rosiglitazone) have demonstrated disturbing side effects in man, however, including liver problems (Script No. 2470, 1999, Sep. 8th, 25).
A large number of hypoglycaemics have significant side effects (hepatic, cardiac, haematopoietic), which limit their long-term use in the treatment of non-insulin dependent type II diabetes.
The development of new therapeutic agents that are less toxic and that are active over the long term is absolutely necessary in this pathology.
Moreover, hyperlipidaemia is often observed in diabetics (Diabetes Care, 1995, 18 (supplement 1), 86/8/93). The association of hyperglycaemia and hyperlipidaemia increases the risk of cardiovascular disease in diabetics. Hyperglycaemia, hyperlipidaemia and obesity have become pathologies of the modern world marked by the intake of food in large quantities and a chronic lack of exercise.
The increase in frequency of those pathologies calls for the development of new therapeutic agents that are active in such disorders: compounds having an excellent hypoglycaemic and hypolipidaemic activity whilst avoiding the side effects observed with thiazolidinediones are consequently very beneficial in the treatment and/or prophylaxis of those pathologies, and are indicated especially in the treatment of non-insulin dependent type II diabetes for reducing peripheral insulin resistance and for normalising glucose control.
In addition to the fact that they are new, the compounds of the present invention meet the above pharmacological criteria and are excellent hypoglycaemic and hypolipidaemic agents.